Overexpression of EaDREB2 and pyramiding of EaDREB2 with the pea DNA helicase gene (PDH45) enhance drought and salinity tolerance in sugarcane (Saccharum spp. hybrid)

Abstract

EaDREB2 overexpressed in sugarcane enhanced tolerance to drought and salinity. When co-transformed with plant DNA helicase gene, DREB2 showed greater level of salinity tolerance than in single-gene transgenics. Drought is one of the most challenging agricultural issues limiting sustainable sugarcane production and can potentially cause up to 50 % yield loss. DREB proteins play a vital regulatory role in abiotic stress tolerance in plants. We previously reported that expression of EaDREB2 is enhanced by drought stress in Erianthus arundinaceus. In this study, we have isolated the DREB2 gene from E. arundinaceus, transformed one of the most popular sugarcane variety Co 86032 in tropical India with EaDREB2 through Agrobacterium-mediated transformation, pyramided the EaDREB2 gene with the gene coding for PDH45 driven by Port Ubi 2.3 promoter through particle bombardment and evaluated the V1 transgenics for soil deficit moisture and salinity stresses. Soil moisture stress was imposed at the tillering phase by withholding irrigation. Physiological, molecular and morphological parameters were used to assess drought tolerance. Salinity tolerance was assessed through leaf disc senescence and bud sprout assays under salinity stress. Our results indicate that overexpression of EaDREB2 in sugarcane enhances drought and salinity tolerance to a greater extent than the untransformed control plants. This is the first report of the co-transformation of EaDREB2 and PDH45 which shows higher salinity tolerance but lower drought tolerance than EaDREB2 alone. The present study seems to suggest that, for combining drought and salinity tolerance together, co-transformation is a better approach.

Sugarcane Water Stress Tolerance Mechanisms and Its Implications on Developing Biotechnology Solutions

“…In all of them, the chosen gene is associated with water stress responses or known to be conferring water stress tolerance in other species (Zhang S. Z. et al, 2006; Reis et al, 2014; Augustine et al, 2015c; Ramiro et al, 2016). In this context it is important to note that a transgenic sugarcane line carrying choline dehydrogenase, claimed to be conferring water stress tolerance, probably will become the first commercially grown transgenic sugarcane in the world (B. Sugiharto, personal communication).…”

“…The AtDREB2A CA (Constitutively Active) overexpression enhanced drought tolerance in sugarcane, as demonstrated by higher relative water content (RWC), photosynthetic rate, sucrose content and bud sprouting, without any negative effect on biomass accumulation (Reis et al, 2014). Also, the overexpression of Erianthus arundinaceus DREB2 gene increased drought and salinity tolerance in sugarcane (Augustine et al, 2015c). …”

“…The increasing knowledge of stress biology coming from genetic, agronomic and molecular biology studies in various crops, including sugarcane is providing a major impetus to develop biotechnological strategies for producing water stress tolerant and commercially useful sugarcane varieties (Lakshmanan and Robinson, 2014; Augustine et al, 2015c; Ramiro et al, 2016). Plants have evolved various drought tolerance strategies, such as changes in life cycle, modulation of growth and development to match with water supply, regulation of whole plant functions to balance resource allocation for growth and stress adaptation, and evolution of stress signal perception for rapid and long-term expression of stress tolerance (Hirayama and Shinozaki, 2010; Hu and Xiong, 2014; You and Chan, 2015).…”

“…Plants have evolved various drought tolerance strategies, such as changes in life cycle, modulation of growth and development to match with water supply, regulation of whole plant functions to balance resource allocation for growth and stress adaptation, and evolution of stress signal perception for rapid and long-term expression of stress tolerance (Hirayama and Shinozaki, 2010; Hu and Xiong, 2014; You and Chan, 2015). The expanding knowledge base helped to identify key genes associated with drought tolerance and maintenance of growth under water deficit condition in various crops including sugarcane (Wang et al, 2003, 2016; Yamaguchi and Blumwald, 2005; Hu and Xiong, 2014; Augustine et al, 2015c; Ramiro et al, 2016). Biotechnology and molecular breeding techniques are useful tools to enhance crop productivity under drought stress.…”

Expression of Pennisetum glaucum Eukaryotic Translational Initiation Factor 4A (PgeIF4A) Confers Improved Drought, Salinity, and Oxidative Stress Tolerance in Groundnut

“…Multiple stress responsive genes such as OsAlfin (alfalfa zinc finger), PDH45 and PgHSF4 ( Pennisetum glaucum heat shock factor) simultaneously expressed in groundnut conferred tolerance to simulated drought stress and enhanced yield (Ramu et al, 2015). Constitutive expression of PDH45 gene along with EaDREB2 was conferred higher salinity tolerance in sugarcane (Augustine et al, 2015). …”